88 
common surface. They vary in colour from a light olive 
to a dark green, and are rather more transparent than wax, 
which otherwise they much resemble. The specimen gives 
out an odour'like that sometimes inhaled on the sea coast. 
The matrix is chiefly cubic Sulphuret of Lead and brown 
Ochre. My specimen, which has the elongated crystal No. 3, 
is principally composed of Quartz with some spicule of 
Carbonate of Lead. 
The Corneous Silver Ore is composed, according to 
Klaproth, of 
) Silver We) hai Goss 
Oxideiof Irani) \.\/ 34 6-00 
Muriatic Acid .- . 21°00 
Sulphuric Acid . 0°25 
Alienatinas. Loy ie Vaya 
Bime ae) ee eu te ONOrs 
95°00 
Its specific gravity is from 4°745 to 4:084. Brissom says 
4°7488. 
The Silver may be very readily extracted from this or€ on 
Charcoal, with the addition either of Iron or of a fixed Al- 
kali, by the blowpipe, when a feetid odour passes off, and 
leaves the Silver in a ¢lobule or globules *. 
It is found in France, Spain, Norway, Hungary, Bo- 
hemia, and Siberia, and also in America; but Cornwall is 
the only county in England, or indeed in Great Britain, in 
which it 1s found. This mineral was once very abundant 
there, and the Silver produced from it has been wrought 
into a tea-table equipage, &c. 
We are the moreobliged to Mr. Williams for the use of 
the present specimen, as it clearly elucidates the form of 
the crystals, which were scarcely determined before. 
* One of my specimens has the Silver so mixed with Ochre, as not to be 
discerned by the eye. When a morsel of this was heated red hot, the Silver 
oozed outin minute globules, giving the fragment a very pretty appearance: 
rubbing gently with moistened Zinc also detects the Silver, by reducing it 
to the metallic state. 
